Clearing multiple TextBox on single click of Button in ASP.Net

Put the TextBoxes inside Panel control

    <asp:Panel ID="Panel1" runat="server">
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
    </asp:Panel>
    <asp:Button ID="Button1" runat="server" Text="Clear" OnClick = "Button1_Click" />

Then import the namspace

using System.Linq;

And on Button Click use the following code

    protected void Button1_Click(object sender, EventArgs e)
    {
        foreach (TextBox textbox in Panel1.Controls.OfType<TextBox>())
        {
            textbox.Text = string.Empty;
        }
    }